The present invention relates to a connecting device for retaining the hauling straps relative to the horizontal reinforcing bars of a handling door of the raisable type, comprising a flexible curtain which can be concertina-folded.
This kind of door generally comprises a metal structure made up of a drive shaft and of several horizontal reinforcing bars which are housed, via sheaths, within the thickness of the flexible curtain.
The horizontal reinforcing bars slide in vertical slideways, the separation of which is somewhat greater than the thickness of the curtain. Provided at the lower part of the door and parallel to the horizontal reinforcing bars is a hauling bar which is connected to the drive shaft via hauling straps which can be wound onto said drive shaft.
Some horizontal reinforcing bars bear connecting devices which are runners or rings through which the hauling straps freely pass in order to allow the flexible curtain to be raised uniformly.
These connecting devices or strap runners consist of a cylindrical sleeve made of plastic secured to a closed flange constituting a free space for the passage of the hauling strap to be retained.
Housings or openings are cut in the thickness of the curtain to allow the strap runners to be fitted to the horizontal reinforcing bars.
The strap runners are identical as regarding their configuration irrespective of the number of horizontal reinforcing bars. The same strap runner can be found on the horizontal reinforcing bar at the bottom of the curtain or on the horizontal reinforcing bar at the top of the curtain.
Thus, the hauling strap, when the door is being opened, lifts the hauling bar which, as it rises, comes into contact with the horizontal reinforcing bar just above it in order to carry it along vertically, and so on as far as the horizontal reinforcing bar at the top of the curtain.
As the door is raised, the strips of curtain which are situated between two horizontal reinforcing bars fold and pile up on top of one another to form a concertina of material.
Inserted between the horizontal reinforcing bars are horizontal tubes or deflection tubes which are free relative to the hauling strap. The function of the deflection tubes is to form and to maintain the fold in the curtain between two contiguous horizontal reinforcing bars as the door opens.
When the flexible curtain moves vertically, it can be seen that the strap runners knock together, considerably increasing the operating noise of the handling door. The deflection tubes at the bottoms of the folds constitute a rigid sill which may present collision risks to people passing through the door while it is moving.
Some doors make it possible to eliminate the deflection tubes by fitting articulated stays which are fixed to the horizontal reinforcing bars.
These solutions are costly and have the drawback of damaging the curtain where the arm of the stay rests against it.